Modern mobile terminals are capable of providing network access to a plurality of communication networks. For example, there are mobile terminals which are capable of providing network access to second (2G) and third generation (3G) mobile telephone communication systems and additionally to a wireless local area network (W-LAN).
In order to avoid setting up a separate communication network for each network access technology, there are solutions under development which integrate multiple access technologies. However, such solutions provide the challenge that a plurality of mobility management protocols, which are used according to respective network access technologies, have to be handled within the communication network at the same time. One problem of such solutions under development is that they have extensive signalling requirements for handling more than one mobility management protocol at the same time.
A known class of mobility management protocols for packet switched data networks employs a so-called “mobility anchor”. A mobility anchor is a network element which receives data packets for a specific mobile terminal and tunnels them to the actual location of the mobile terminal. Tunnelling means a transmission of data packets intended for use only within a certain target network through another network in such a way that the routing nodes in the other network are unaware that the transmission is intended for the target network. Tunnelling is generally done by encapsulating the target network data and target protocol information within the other network's transmission units.
Protocols according to this class of mobility management protocols include e.g. Mobile IPv6 (MIPv6), Mobile IPv4 (MIPv4) and the General Packet Radio Service (GPRS) Tunnelling Protocol (GTP). MIPv4 is a mobile. Internet protocol (IP) that allows a mobile terminal to continue using its permanent home address as it moves around the internet. Mobile IPv4 is described in document MIPv4-IETF RFC3344 published by the Internet Engineering Task Force (IETF). MIPv6 is a mobility management protocol which was developed as part of Internet Protocol version 6 (IPv6) in order to support mobile connections. MIPv6 is a standard which was designed to authenticate mobile terminals using IPv6 addresses. A detailed description of MIPv6 can for example be obtained from document MIPv6-IETF RFC3775 published by the Internet Engineering Task Force. GTP is an IP based mobility management protocol which is used within Global System for Mobile communication (GSM) and Universal Mobile Telecommunications System (UMTS) mobile communication networks. GTP is described in document 3GPP TS 29.060 by the Third Generation Partnership Project (3GPP).
Although these mobility management protocols have a similar approach on how they manage mobility (for example they all use anchor nodes, tunnelling techniques and location update messages), they differ significantly with regard to additional features which are applicable to various user-specific network scenarios and which were adapted in order to be accepted by certain network operators. For example, GTP is a network centric protocol, in which local network entities, e.g. the Serving GPRS Support Nodes (SGSNs), initiate mobility signalling. Contrary to this, MIPv4 and MIPv6 are terminal centric protocols, according to which mobility signalling is initiated by the mobile terminal. Furthermore, GTP is widely used in 3GPP networks. However, other communication networks do not employ GTP.
Problems arise in case more than one mobility management protocol, and in particular a combination of network centric and terminal centric protocols, will be employed in a communication network. Such mobility management protocols and related messaging will have to be processed and handled at the same time. This requires high processing power within the network elements, and the signalling load increases accordingly. Moreover, in order to route data packets to the desired mobile terminals, a plurality of dedicated mobility anchors in the transmission path of the user plane will become necessary.